It is frequently desirable to surround vessels, such as ships and barges, that are moored at a dock or the like, with a containment boom in order to contain oil or other pollutants from the vessel in the area immediately surrounding the vessel. Such booms thereby simplify the task of cleanup in the event of any spillage from the vessel.
One conventional oil containment boom is comprised of a string of floatable billets, for example of styrofoam, having round cross sections. The billets are covered with rubber impregnated ripstop nylon sleeves or vinyl impregnated woven cloth fastened together to make continuous flexible but strong lengths. The diameter of the billets, of for example 12 inches, and the depth of the skirts vary as a function of various factors such as weather conditions, vessel size, etc. A "skirt" portion of the sleeve hangs downward from the submerged portion thereof, the skirt extending downward for a distance of generally one foot to 18 inches below the surface of the water, depending upon the size of the boom. A sleeve of smaller diameter, for example four inches, is provided at the bottom of the skirt, and length of chain or wire rope is threaded through this lower sleeve, running continuously for the length of the boom.
Tankers and barges utilizing ports on the east coast of the United States generally have lengths in the range of 150 feet to 700 feet. Vessels of this size thus require the use of containment booms that have lengths of from 200 feet to 1200 feet. When a vessel is not moored at the dock, the boom is stored at a nearby location, for example behind a standard "T" dock.
After a calling vessel is secured dockside, the boom is conventionally deployed from a storage area using a 16' to 20' open cockpit skiff having, for example, a 50 to 150 H.P. outboard motor. The skiff is employed to tow the boom around the dockside vessel and connect it back on itself, thus forming a circle around the vessel to contain any spillage.
In the deployment of the boom, it is necessary to secure a number of anchors thereto, such as a #15-#35 Danforth style anchors. These anchors are secured at critical points along the boom by the crew in the skiff, to insure that the boom stays from 30 to 50 feet from the off dock side of the vessel.
Most conventional containment booms are of the configuration, with their dimensions depending upon the application, location, dock size, largest expected vessel size, seas, current, water depth, etc. Generally the boom is left floating while not in use, at a location away from the traffic and the dock face, and yet close enough for deployment. Such storage can result in the boom fouling on itself or on pilings.
The process of booming, or deploying and storing the boom, is usually done by a subcontractor or the marine terminal operator whose employer owns the dock and deploys the boom as an added step to his regular duties. In the process of booming, one or more men must man the outboard skiff, to set anchors to secure the boom with sufficient spacing from the side of the ship. Getting into and out of these boats, especially at low water, employing slimy ladders, etc., can and does cause problems and accidents, not to mention fouling of the anchor lines while setting and pulling the anchors.
Elements such as cold weather and darkness frequently make it dangerous to be in the skiff, let alone to simultaneously maneuver 200 to 1200 feet of boom and set anchors with 150 to 200 feet of line each. Many marine terminal operators assigned to handle the booming are not adequately trained in the use of small boats, thereby increasing the risk of accidents.
Other types of floating containment booms are disclosed, for example, in U.S. Pat. No. 4,068,478, Meyers et al; U.S. Pat. No. 4,964,758, Pekelny and U.S. Pat. No. 5,114,273, Anderson. Such booms are subject to problems in deployment, as above discussed, or are adapted to be deployed only directly from the vessel.
Submersible booms are also known, wherein a collapsible tube is connected to a source of air pressure, such that it will float when inflated and sink to the sea floor when deflated. Booms of this type are disclosed, for example, in U.S. Pat. No. 5,064,309, Dickie et al; U.S. Pat. No. 4,573,426, Larsen; U.S. Pat. No. 3,779,020, Muramatsu et al, U.S. Pat. No. 3,859,796, Benson; and U.K. Patent No. 843,131. While containment booms are not generally subject to the above discussed problems of deployment, they are subject to problems in inflation and deflation as a result of the use of collapsible tubing.